Cutting-edge mixing facility
Friction materials consist of:
- Binders (most often these are finely-ground powdered phenolic resins)
- Fibrous components (e.g. mineral wool, glass fiber)
- Metallic fillers (copper, brass, bronze, steel powders, steel chips, steel wool)
- Lubricants (powdered graphite, petroleum coke, metal sulfides).
- Mineral fillers (e.g. barite, aluminum oxide).
Every friction material formula consists of as many as 10 to 25 ingredients. As can be clearly seen, the number of components is high. That is why it is so important to achieve a uniform and homogenous mixture of the friction material to ensure that the whole volume of the mixture has the same properties in the final product. This demands extremely precise weighing, mixing and delivery of ingredients.
The processing line of the automated mixing facility, which has been in operation in the new LUMAG factory since November 2013, was designed by our German supplier in cooperation with our R&D department. The line is a uniform set of devices housed in a stand-alone steel structure. It performs all operations of the friction mixture manufacturing process, starting from the delivery of ingredients, through loading, dosing, weighing and mixing, to the delivery of the final product. All operations are automatically controlled in line with our quality and production capacity requirements.
The investment is unique on a global scale, as it includes a number of technological solutions never before tested in the real-life manufacture of friction mixtures, ensuring full automation and complete elimination of manual operations. It employs:
- Technology of dosing fibrous components with the use of the FIBERDOS® technology.
- Technology of dozing steel fibers developed especially for the LUMAG project.
The process of manufacturing friction mixtures based on an automated line is one of its kind, because it combines the know-how and expertise of both the supplier of the dosing system and the manufacturer of friction materials.
The mixing facility has an annual production capacity of 14 thousand tones of a friction mixture.
As a part of its development of truck pads, LUMAG focused on strengthening the bond between the friction material and the back plate, under cold and hot conditions.
When a brake pad is manufactured, a friction material is pressed onto a steel back plate. Before pressing, the back plate is degreased, sanded and covered with a special heat-resistant adhesive. During operation under extreme conditions the brake pad overheats and the strength of the adhesive bond is reduced. To prevent shearing of the friction material, the surface of the back plate has to be shaped properly. Various solutions to this problem are adopted in the industry: spigot holes, back plate perforation through shearing, welded mesh, over pressing with bulk heat treatment, back plate casting with peg-shaped fixing elements, peg/stud welding, powder coating, to name but a few.
Thermal drilling is a method, patented by LUMAG, of forming the brake pad’s back plate with special-purpose thermal drills. The drill bores into the pad’s back plate, causing localized melting of the steel. Next, plasticized back plate material is pushed by the drill over the surface of the plate, forming a conical-shaped flash, ending with a flange on its top edge. At the same time, a conical hole is made in the plate.
Forming the back plate in this way offers excellent characteristics, significantly improving the adhesion of the friction material to the back plate:
- A conical hollow in the plate material and a flash above its surface improve the resistance of the friction material to shearing forces acting parallel to the plate.
- A flange-shaped ending of the flash is filled with friction material during pressing, which increases the material’s resistance to forces acting perpendicular to the back plate surface.
Friction material formulas are a compromise between a manufacturers’ technology, including product costs, and the high, and often contradictory, end-user requirements. LUMAG, as a manufacturer, invests in cutting-edge machinery, which allows us to eliminate almost all technological limitations.
Buses and municipal vehicles, especially inner city vehicles, brake often. High temperatures can result. The requirement for thermal stability of the friction material is higher. It has to continuously operate in the range of up to 400°C, sometimes in temperatures reaching 750°C. High working temperatures and increased frequency of braking may cause greater wear and tear. LU 903 is the material of choice. It is designer for such applications, with a lower friction coefficient than typical CV materials. Brake pads in this material feature chamfers which reduce the risk of squeal. Additionally, brake pads using this material were designed with the comfort of bus passengers and drivers in mind, since it reduces the risk of vibration and squeal during braking.
LU 801 is a modern friction material meeting the requirements of brake manufacturers for OE installation in vehicles.
The material boasts:
- Environmentally friendly composition, free of heavy metals, such as antimony
- High cold and hot braking efficiency, in temperatures reaching as high as 850°C, as proven by the simulation of a downhill descent from the Rossfeld mountain,
- High braking efficiency across the whole range of speeds used
- High resistance to wear
Top quality of our products is attested by ISO 15484-compliant tests performed on a dynamometer equipped with a Knorr SN7 station with 10 tons of axle load.